S.D. Codified Laws § 32-3A-18
Classification of boats for equipment purposes
Boats subject to the provisions of this chapter are divided into four classes as follows:
Class A. Less than sixteen feet in length.
Class 1. Sixteen feet or over and less than twenty - six feet in length.
Class 2. Twenty - six feet or over and less than forty feet in length.
Class 3. Forty feet or over.
Source: SL 1959, ch 125, § 5; SDC Supp 1960, § 25.1405 (1); SL 1984, ch 279, § 17; SDCL 42-8-23 .